


Structures Built For Combustion

by whatisthisnightmare



Category: Katekyou Hitman Reborn!, 僕のヒーローアカデミア | Boku no Hero Academia | My Hero Academia
Genre: Alternate Universe - Canon Divergence, Alternate Universe - Reincarnation, Author Hates Bnha Canon, Author wrote this instead of doing homework, BAMF Gokudera Hayato, BAMF Yaoyorozu Momo, Bakugou Katsuki & Midoriya Izuku are Not Childhood Friends, Bakugou Katsuki is Bad at Feelings, Betaed, Character Study, Character building, Crossover, Dead Dove: Do Not Eat, Does Reincarnation Count as Character Death?, Dying Will Flames (Katekyou Hitman Reborn!), Gen, Good Parent Bakugou Mitsuki, I suggest reading entire work style, Implied/Referenced Character Death, Mafia is Dangerous, Mentions of CEDEF, Mentions of Tri-ni-sette, Mentions of Varia, Mentions of Vongola - Freeform, No Romance, Not Canon Compliant, Platonic Relationships, Pre-Canon, Quirks (My Hero Academia), Reincarnation, So is the Underground, Some Plot, Tired Tsukauchi Naomasa, Worldbuilding, Yaoyorozu Momo is a Good Friend, read the tags, too many tags
Language: English
Status: In-Progress
Published: 2021-03-10
Updated: 2021-03-10
Packaged: 2021-03-16 15:21:13
Rating: Not Rated
Warnings: Creator Chose Not To Use Archive Warnings
Chapters: 4
Words: 5,320
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/29951949
Author URL: https://archiveofourown.org/users/whatisthisnightmare/pseuds/whatisthisnightmare
Summary: When a building burns, it burns everything along. When a person changes, so does everything around them. A ripple can change the whole damn flow, much less a soul burning with Will.And fuck, because Mukuro was right all along. Reincarnation is a thing now.
Relationships: Bakugou Katsuki & Bakugou Masaru & Bakugou Mitsuki, Bakugou Katsuki & Yaoyorozu Momo, Other Relationship Tags to Be Added
Comments: 17
Kudos: 52
Collections: Identity Crisis





	1. Nitroglycerin

**Author's Note:**

> I've read a lot of fanfiction where Hayato is reincarnated as Bakugou and decided to try. Why? Because I already have like a whole Google Doc filled with it.
> 
> Slow-paced, mind your steps. 
> 
> And of course, some applause for my betas Wish_I_Was_Orochimaru and randomwaffle3!

[][][][]

Gokudera Hayato had lived a satisfactory life.

It hadn't been _great_ , much less _good_ , but satisfactory nonetheless. He'd served his Sky well, and the Eleventh Storm had a reasonable head on her shoulders. Dying from cancer of all things was a bit embarrassing, but he'd dealt with it. Takeshi, the damned baseball freak, had actually _cried_. Even that jackass Cloud was subdued. He'd like to think it was the old age getting him sentimental, but no, he knew that in his heart of hearts, just like how Tsuna was _his_ , they were too.

Breathing his last, the explosive Storm, the last of G's vicious bloodline, shut his eyes for the final time to the ragged sobs of his beloved Boss and the sorrow of the remaining Guardians.

Worlds away, a baby with sharp red eyes breathed his first.

[][][][]

When Katsuki was seven months old, the first word he said had been, to the everlasting bemusement and confusion of his parents, "J- Ju- Juudaime!" Where he'd even learned numbers they didn't know, but their baby was obviously a genius- those eyes were too sharp for a simple babe. "Juudaime? What next, doing algebra?" Bakugou Mitsuki had joked, not knowing it would soon become spot-on.

Katsuki, the ever-curious child, had just stared quietly. Too quietly. Like he understood. But the Bakugo matriarch waved her worries away- for all she knew, Katsuki could have some intelligence quirk.

[][][][]

Katsuki was one when he started to talk, and to walk. And walk he did. The Bakugous were in constant dangers of heart attacks every time their only son disappeared off to run around the street. He tired easily, which meant ending up resting in the oddest of places- Masaru had once found him hidden under the bushes of the nearby park. How and why was not answered, and soon the Bakugous accepted it as one of the many oddities surrounding their child.

Despite the weirdness, they still loved him very much. Mitsuki would regale him with stories from her office, while Masaru told him about the pains of paperwork. They were reasonably well-off, with Mitsuki working as a small-time lawyer and Masaru as the editor f a famous fashion magazine. That meant indulging Katsuki, whose eyes lit up at any odd gadget- which was a lot. He'd spend days fussing over any new, shiny electronic the Bakugous bought him, and would be sufficiently distracted from wandering. These bouts of attraction didn't last long, however, and soon he resumed his previous exercises.

[][][][]

This continued until he was five, and his quirk manifested. Mitsuki could still remember the moment her darling child walked up to her, tears rolling in his eyes, and presented his scarred palms.

They’d explained about quirks, of course, but with their passive quirks they'd expected his to be something of the sort- sweat-based, or something involving chemicals. Not exploding nitroglycerin. That was poisonous and flammable enough to make little Katsuki a walking bomb.

They made sure to visit specialists and talk about control, doctors to understand how the chemicals endangered his body, chemists to check the levels of corrosivity. Back home, they made sure he bathed at least thrice a day, and washed his hands periodically. Learning to control sweat glands was Masaru's job- his quirk was closer to Katsuki's. Mitsuki fended off anyone _too_ interested in her son's quirk.

[][][][]

Katsuki had always brushed off the existence of Quirks. Sure, they were interesting, but they didn't really affect his life- he preferred to scour over the very unique new tech they'd developed. Until his fifth year in this world.

Needless to say, the explosions had caught him off guard. He'd noticed his sweat being weirdly _sweet_ , but thought it was just the fact he'd have some skin-coating like his mother. And then the explosions started. This barely trained, weak adolescent body was not fucking ready for them. It _hurt_ , like he'd been struck with a stray bunch of dynamite, and didn't have Storm flames to burn it away nor Sun to help lower the pain.

He'd ran to his parents- a civilian life as a baby had really softened him- trying hard to hold in his tears. They'd brought him to doctors and specialists, and in the end he went home with a brand new Quirk- Explosions.

He would've laughed at the sheer irony for the Smoking Bomb to actually become a literal bomb, if not for the fact he'd have to train his Quirk too. How annoying. He might be an over-achieving genius, but living as a baby had given him a sense of laziness. A contented life, was his goal this time round. Well, that and maybe upholding Juudaime’s ideals because, frankly, the so-called Heroes of this world are mostly freaking useless.

[][][][]

Heroes and villains were just stepping stones.

He couldn't shed his roots- no matter what he was Mafia through and through. He could uphold Vongola and Juudaime's policy here, though. He would show this world what true Mafia was made of.


	2. Copper Sulfate

**Summary for the Chapter:**

> Adding copper sulfate to a fire produces vivid green flames. No sparks of lightning, sadly.

**Notes for the Chapter:**

> Enter Midoriya Izuku. Fear not, he is going to be a major character... For this chapter. Sorry, but after this he's going to only get cameos for his POV. My chemistry teacher's gonna be so proud I finally decide to use what she taught me.
> 
> WARNING: CHARACTER BASHING WILL HAPPEN. I'm not afraid to admit I ain't a fan of Midoriya. If you are interested in this fic but don't want to see any bashing, SKIP THIS CHAPTER. It won't affect much of what you need to know about the plot.
> 
> READ END NOTES.

[][][][]

It was during one of his wandering, a few months after his fourth birthday, that he found a toddler around his age. Green-haired and teary-eyed, Midoriya Izuku looked and felt so like Tsuna it _hurt_. Katsuki had nearly fainted from shock at the thought of his Sky reincarnating as well. Because it would mean he'd _died_. And that was not allowed to happen! Tsuna deserved a rest of peace in whatever afterlife! Not reliving being a baby!

So, it was great relief when he figured out they were completely different. Sure, there were similarities of Tsuna-before-Reborn and Izuku, but it was very clear to the loyal Storm they were as different as Sky and ground. They had caring mothers and absent fathers, but unlike Tsuna who did his best to help Nana, Izuku just sat there doodling in his notebooks or watching television. Tsuna was easily spooked, yes, but he was not cowardly. Izuku cried at every single thing, and rolled away from danger whereas Tsuna would just endure it. Izuku wailed and bawled constantly, while Tsuna held in everything. Izuku puttered and pattered for attention, but Tsuna, he despised it.

He couldn't help it- he antagonized the kid.

He ignored the offers to play together as fucking _Heroes_ , of all things. Even cosplaying turf-top would be a better alternative. Yet the kid still _demanded_ his attention, as if he was fucking _entitled_ to it just because they were neighbors. Katsuki had told him to fuck off very, very politely several times, mindful the greenette was still a child, but the brat had to _ignore_ it. And then complained about not having friends. There were other kids, who had also been chased away by the idiotic clinginess- if he wanted everyone to like him, he should've at least tried to change himself!

But no, the kid just went crying to his mother. This was why other kids disliked him, heavily- he relied too much on his mother than the other kids were used to until it was rather uncomfortable, he didn't seem to understand how to properly socialize, and didn't have a single concept of privacy of others, nor respect for personal space. He wrote down everyone's Quirks and broke it down right in front of them! Katsuki could appreciate the attempt at analysis, but not if the guy was also a stupid bastard. Could he not see how others were angry at his invasion of privacy? And then he had the actual guts to cry about being rejected! If it were anyone from his old world, the kid would be dragged to the back-alleys and beaten up.

All in all, Katsuki was now fucking stuck with an obsessed, clingy _fanboy_ of all things, just because he was the only one who could tolerate the boy's lack of respect thanks to his maturity. It irked him, but he couldn't just harm a civilian unless attacked- did violation of personal space counted as hostility?

Katsuki tried to advise the kid, really. But Izuku never listened- all he did was nod along, slightly subdued to sniffling instead of all-out bawling, before he would return to his ways. It wasn't that Katsuki couldn't sympathize- but the boy put all his effort in the wrong places and didn't even listen to anyone! His mother indulged him too much- and coddled him until not only was he naïve, he was downright oblivious to his own shortcomings. No wonder he was Quirkless- this sort of person could never handle power.

[][][][]

Izuku stared at Katsuki's leaving back and couldn't help it- he started crying again, even when the blonde had yelled at him to stop. It wasn't his fault he cried easily, he really tried to hold it in! But no matter, Katsuki was now gone _gone_ **gone** \- his only friend, who never pushed him away....

"It's alright, Izuku," Mom whispered, gently squeezing his shoulder. "I know you're sad, you should just let it all out. Katsuki is just stubborn- he'll come around soon. My baby, my poor baby, it's okay. I've got you." Inko smiled softly at her son. Izuku tearfully smiled back. "Thanks, mom," he murmured. "Anything for my baby," Inko beamed, glad her son had stopped crying. She knew it wasn't very good for Izuku to keep crying all the time, but it was better than keeping it all in. He'd grow out of it, she reassured herself.

Izuku, oblivious to his mother's conflicting thoughts, stared after Katsuki. Why wouldn't anyone want to be his friend? He even shared his Hero Analysis for the Future with them! They all pushed him away, and even Katsuki had _scowled_ at him! Katsuki had even scolded him- but what was wrong with sharing? Mom said sharing was caring. Katsuki was a kid too- he was allowed to be wrong. He didn't even like Heroes! But even if he was weird, Katsuki was his _friend_. And Izuku would _never_ abandon his friends like the villains on TV.

**Notes for the Chapter:**

> READ THE NOTES.
> 
> Ok, I hope y'all don't blame Inko. She's under a lot of stress as a single mother with an extra-clingy child. Yeah, Izuku is damn clingy. Also- something I really was confused by was his behaviour. I also used to speak what I thought when I as a kid, so I don't blame him for that, but learn to control your own damn mouth. I grew out of it when I was, I dunno, in kindergarten, and he can't even do it as a high-schooler? Fuck man, it's your own body. Yeah it's a characteristic, but I still highly dislike it. Plus, he isn't the only one able to analyze Quirks. I don't get the hype about it. Even I, an idiot who reads manga and writes fanfiction, can do it. I just don't keep a notebook. Sorry for ranting, but I promise the bashing will last only for this chapter. Because imma leave him alone after this apart from a few neutral cameos. However, in the upcoming chapter there will still be some not-very-neutral ones, but it won't be bashing.


	3. Obsidian

**Summary for the Chapter:**

> Borne from the felsic lava of volcanoes. Cooled into shards of black crystal.

**Notes for the Chapter:**

> Enter Yaoyorozu Momo. One of the best girls of bnha. The best thing going for it is Horikoshi-sensei's character building. Can't beat that.

[][][][]

Katsuki grinned. He'd successfully skipped a grade- and now he could graduate a year early Who wanted to stay with snot-nosed brats? And even more, he would be transferring to a more advanced school too! Now he wouldn't have to be in the same building as that damned crybaby. He'd thought the kid would grow out of it, but while he'd mellowed a little, the waterworks still spouted whenever Katsuki so much as looked in his direction. Annoying.

Due to the location of the school, he would have to wake up earlier and come home later- but that was fine with him, considering the fact he won't have to see so much of the broccoli-lookalike anymore. The trash would probably come crying again, but he’d put up traps around his house and locked every window and door. Even his parents who usually just brushed off the crybaby's behaviors understood his want for privacy and were downstairs in case.

Katsuki smirked. One good thing this life gave him was his loving parents. He'd never truly understood why it was so nice to have parents until now. It was.... nice, to have a trusted adult watch his back. Weird, but nice.

He quickly started scrolling through the school website to order his uniforms and books online. The things from his now ex-school would be given to one of the poorer students. Anything but the broccoli.

[][][][]

"This is our new student, Bakugou Katsuki. Bakugou-kun, why don't you introduce yourself?"

"You heard my name. Don't mess with me and I won't mess with you."

"...Ah, um, you can sit next to Yaoyorozu-chan. Now, everyone open your textbooks to page 17..."

[][][][]

Yaoyorozu Momo had skipped a grade, and it was the first time she'd seen another student who skipped grades too. And a transfer! How curious!

"I'm Yaoyorozu Momo," she introduced herself politely, "Nice to meet you." "Bakugou Katsuki. Yaoyorozu Corporation?" Momo blinked- that was fast. Even if Yaoyoruzu Corp. was quite famous in the business industry, it wasn't exactly of interest currently to the other kids. "Why yes. You are... Bakugou Mitsuki's son?" The blonde was surprised. "You know my mother? Let me guess, the Yaoyorozu invention competition copyright incident."

"Yes." Momo replied, "I really admired her straightforward way of defending. It was quite refreshing compared to the usual diplomatic lawyers father calls." "I suppose so," Bakugou hummed. "Say, I heard that your parents are going to sponsor Clavell Project. It's an interesting choice- although I doubt anyone but the competent ones will actually invest in their products, it definitely is innovative." "Yes, I know right? The Hero Commission and Hawks's Agency along with a number of underground agencies have already bought some prototypes, mother believes it is a good investment and I agree too!"

"Yes, intelligence-based Support items are hard to come by these days." Bakugou sighed, "The fact they even decided to do it is already amazing. Although there are truth Quirks already, a device that reads the verbal tics and comes to conclusions is extremely smart. It would be dangerous if fallen in the wrong hands, though." "The Hero Commission and my parents are already seeing to security measures," Momo beamed, clearly glad to find someone to share it with, ""You could even come see! I'm sure mother would be partial to my friends."

And that, was the start of a partnership that all would tremble before. But right now, they were two not-so-naïve children, albeit with one of them quite older mentally, and to the adults it was a blossoming friendship.

[][][][]

Izuku paused, fidgeting with his sleeves nervously, before pressing the doorbell. There was a sound of footsteps, then the door swung open. "If it isn't Midoriya-kun!" Bakugou Mitsuki grinned down at him. "What's up?"

"A-ah, is Katsuki home?" Izuku asked, voice trembling slightly. "No, the brat is with that new friend of his. They're gonna be gone for the whole day, what do you need him for?" Izuku flinched. A... friend? Katsuki didn't _do_ friends. The only one close to him was Izuku! "W- what do you m-mean?" "Exactly what I said, kid, the brat's off doing who-knows-what with his new friend." Mitsuki snorted.

Izuku snapped out of his shock. "U-um, w-where has Katsuki been? He h-hasn't been coming t-to school..." "He transferred." Mitsuki answered, unknowingly breaking the last string of hope in Izuku, "He skipped grades and went to that elite school uptown."

Izuku couldn't help but feel betrayed. Katsuki had transferred _without telling him_! And he'd been so _worried_ , that the other boy was sick, or had some accident... And he _just went away_! He _abandoned_ Izuku, his only friend! And even went to- to _play with someone else_ , when he kept turning down _Izuku's_ offers! Why! He stumbled away from the door, face slightly green, before dashing home. Mitsuki, still rambling on about brats and sleepovers, watched him go with eyes narrowed.

[][][][]

Katsuki didn't smile, but it was an expression close to awe he had on while touring one of the main Yaoyorozu factories. "Amazing, isn't it?" Momo beamed, proud of her family's work. "Come on, we still have another section!" Katsuki nodded, letting himself be pulled along as he watched the workers put together a medical scanner. He had managed to get his mother to let him come visit the factory with Yaomomo-san. He'd coined the term, lazy to keep wasting breath on 'Yaoyorozu-san', which he'd have to call the girl's parents. It would be confusing. So, he'd made a nickname, and the Yaomomo had been very accepting.

"I can't believe this! Our dear daughter bringing home a friend!" Yaomomo's mother, the lioness of Japan's business industry- Yaoyorozu Mikoto. With guts of steel and a tongue sharper than knives, she'd climbed her way up with a pair of shiny black heels and now stood on a not-so-figurative mountain of bodies. Katsuki bowed respectfully- he wasn't anyone in this life, which was something he'd have to remedy sooner or later.

"Now, now, dear, no need to overwhelm them," the Yaoyorozu Boss smiled genially, but his eyes were sharp. Yaoyorozu Mori was not a man to be trifled with. The Boss of Yaoyoruzu Corps. and the main sponsor of the Hero Commission, he had contacts all over Japan and who-knows-how-many favors in his pocket. Unrelenting and intelligent, he would've been a good head for CEDEF. Take it from someone who knew Hibari.

It was slightly eerie how everyone in this world looked like carbon copies of their parents- and Yaomomo was no exception. If Katsuki was a male Mitsuki, Yaomomo was a female Mori. Same slanted grey eyes, thick black hair- although apparently, she'd inherited the bangs from her mother.

"The son of Bakugou-san, hm?" The Yaoyorozu Matriarch hummed, eyes wrinkling as she smiled slightly. "Just call me Mikoto. Yaoyorozu is _such_ a mouthful." And there, that was a subtle, subtle threat if Katsuki wasn't wrong. And if he was wrong, he'd eat Hibari's tonfas. Hinting at the Yaoyorozu's name... a simple but effective method as an opening, that would scare off any idiots. If they were the people who raised Yaomomo, no wonder the girl was so advanced. It was like talking to a calmer, less traumatized Chrome. Which had been why he'd let her claim him as a friend.

"How was the tour?" Yaoyo- _Mikoto-san_ questioned, eye-smiling. Katsuki grinned, "It was very nice. I thank you for the chance to come visit. It was an illuminating and satisfying experience. There was a bit of surprises, but I'm sure of the safety" Translation, thank you for not kicking me out or gutting me. I will try to be careful.

Mikoto-san nodded, seemingly content for now. Yaomomo narrowed her eyes- "No threatening my friend, mother!" "Aw, we were just talking!" Her mother pouted, leaning on her husband, "Dear, I'm being accused by my own daughter! Whatever shall I do?" The patriarch just chuckled. Yaomomo scowled, "You didn't say wrongly accused." "So, I didn't," Mikoto-san replied, amused. "Well, it looks like we've been rejected in favor of lil' Bakugou. Let's go back, Mori, I don't think my heart can take it."

Yaomomo rolled her eyes. "I promise they're not always like that," she whispered to Katsuki. "It's fine," Katsuki answered. "It was an honor to meet you," he added to the two parents. Mikoto-san giggled and called him a darling polite child, while Mori-san just nodded. "You two can go to the training room," he told them, getting up, "Momo, your mother and I will be in our offices."

"Training room?" Katsuki murmured, curious. "Yeah, father made me one when I decided to become a Hero."

[][][][]

Izuku bit his lip as he scribbled down another chapter about Katsuki's quirk. He'd already did his best, but he had only ever gotten to around five bullet points before giving up. Katsuki rarely used his quirk, so even though the name was self-explanatory, Izuku didn't really have a lot of information. He knew Katsuki trained his quirk- his mother had confirmed it. But Izuku could never find _where_.

As he scratched out yet another theory, Izuku could feel the tears coming. Drops of water splatted down onto his notebook, and he really, really wanted to just curl up and cry. After all, mom had said it was _good_ to let out his emotions. But... it was _his crying_ that drove Katsuki away. That made him _leave_ him for another friend, who wouldn't cry, who wouldn't mutter about quirks. Izuku wasn't _stupid_ , unlike what some of his teachers and classmates thought. He knew people stared and talked whenever he started muttering, or when he started crying after someone laughed at him.

Maybe... maybe mom had been wrong. Adults rarely were wrong, but mom had said nobody was perfect and that was okay. Katsuki wasn't perfect. Izuku knew that, but... Katsuki may as well be. After all, he himself was too imperfect. A near-perfect person should be friends with a near-perfect person- it would be _right_. Like how the hero and heroine _always_ got together in movies. Sobs escaped his lips as he gave in and hugged himself, rocking back and forth as he cried.

[][][][]

Katsuki eyed the so-called training room apprehensively. A wide grey room with reinforced walls and all-sorts of training materials scattered about neatly, it was clear that it had been made professionally. He bent to pick up a huge encyclopedia next to the weights. “What, you lift books too?”

“Oh, that,” Blushed Yaomomo, “It’s for my quirk. I have to know the atomic formula for an object’s make-up to create it perfectly.” Katsuki raised an eyebrow. “Sounds damn complicated. How much can you make?” “A few simple objects,” Yaomomo replied. “I can make a Russian doll, a metal rod, a metal plate, a small glass bottle, and I’m currently learning to make a flashlight.” Katsuki nodded approvingly. These objects, apart from the Russian doll, were all made to be versatile weapons on-hand, or could help with emergency situations easily. “Not bad,” he grinned, “I can help you with the flashlight.”

“Really? Thanks. Most people just... shy away from the work.” Yaomomo smiled, embarrassed. Katsuki huffed. “I’m not most people now, am I?” “You sure aren’t,” The girl giggled. She handed over a notebook, and flipped to the bookmark. “Here, the list for the components and the structure of a flashlight...”

[][][][]

And the two stayed there until Mitsuki came to pick up her son, chatting over chemical equations and how to kick ass with a metal staff. The Bakugou matriarch just smiled at the sight of her usually anti-social son bonding with someone his age. “They really get along, don’t they?” Mikoto-san hummed, and the strict woman had a soft look in her eyes. “Guess the saying geniuses attract is real,” Mitsuki snorted. The two women watched their children squabble over what to learn next- Katsuki wanted to learn to make dynamite, Yaomomo wanted to learn to make a pen.

“They’re going to be terrifying when they grow older,” Mikoto sighed. And Mitsuki could not find any reason to dispute the fact.

**Notes for the Chapter:**

> Yay Yaomomo! Seriously, she just strikes me as a tiny genius. Also, apparently you can't skip grades in Japan, but it's not like bnha is irl Japan. They have fucking superpowers and an animal can become a principal of a high school, how about those with intelligence Quirks? Hm? Basically, logic doesn't apply easily in bnha. Keep that in mind while reading. And yeah, Clavell is basically a play on clever.


	4. Strontium Chloride

**Summary for the Chapter:**

> Used in flares and fireworks, a maelstrom of scarlet and crimson. We look and think of anger and blood and missed happiness.

**Notes for the Chapter:**

> Enter vigilantism. A bit of a huge leap, I'll admit. Seen from different views, from alternating eyes. Yes, there is a subtle time-skip.

[][][][]

Katsuki shifted from his spot atop the roof of a random building. He fingered his new sticks of dynamite that he’d managed to convince Yaomomo to make. Now nine years old, he was ready to bring back the moniker of the Smoking Bomb.

Adjusting his scarf, he swiftly dropped into an alley where a woman was going to pass. She was a college student- probably went out for a ‘night of fun’, unaware of the man stalking behind her. He’d started his vigilantism by stopping petty thefts in the evening, and he’d been monitoring this neighborhood- the stalker had already molested several victims. Thankfully rape hadn’t happened yet, but he wouldn’t put it past him.

As he’d predicted, the stalker lunged forward the moment the woozy woman stepped into the opening to the alley, hand covering her mouth as he pulled her in. Katsuki scowled and loomed from behind like a monster from the darkness, and easily bashed in the stalker’s head with a metal staff. Mentally thanking Yaomomo again, he swiftly took the moment to push the woman out of harm’s way.

Lighting a stick of dynamite, he waved it in front of the startled man’s face. “Kaboom,” he whispered, grinning fiendishly. The man shrieked and tried to run, but a kick to his ankles brought him down. Katsuki dropped the dynamite onto his hands, “Allow me to help you cleanse them.” There was an explosion, and the man cried out at the sight of his charred, blackened hand. The dynamite hadn’t even been of best quality- it was just a soft one that fizzed off. Katsuki smirked- this guy wasn’t going to commit any crimes now.

He walked over to the stunned woman. “Names the Smoking Bomb,” He offered, “Next time be more careful and try to be with friends, hm?” He patted her shoulder, handed her a spare penknife, and disappeared off into the shadows. The woman stared, still gripping the penknife. “T-thank you...”

[][][][]

Naomasa kneaded his forehead, staring at the reports in front of him. There was a new vigilante roaming Musutafu now- moving exclusively at evening and night. The people were calling him the Smoking Bomb, and despite the fact that his actions were very, _very_ vigilante-like, he couldn’t legally be ruled as one. Why? Mainly because the brat used fucking _dynamite_ instead of his quirk.

He should be asking where in hell the brat got his dynamite, and in those amounts- and yes, it was clear the not-vigilante was a kid. However, it was clear the kid was spooked at every mention of Hero or law enforcement, from the way he dashed away at the slightest mention of them. So, a distrust of the law. Which would make it a hundred times more difficult to get information.

The worst thing? People supported him. It wasn’t actually the worst thing (kid in the streets, alone, at night, anyone?), but it would make it harder to find him or convince him to stop his vigilante activities. Especially because he was really, really good at it. Even better than some Heroes he could name, which was worrying in itself.

But setting all these aside, he was most worried about what one of his... less legal informants had given him. Apparently, the boy was also digging into the Underground. He’d been seen near even fucking _Giran_ , who was renowned for his critical eye for the highest bidder and unbeatable secrecy. If even Giran had accepted the kid... He shuddered to think what would happen after the kid grew up. He really wanted to retire early- the future generations were damn scary.

He took another look at the pile of paperwork beside the reports and raised to get a coffee. It was going to be another long all-nighter.

[][][][]

Yaomomo stared at the faint slants of moonlight from her bed. It had been two hours after Katsuki’s patrol started, and she couldn’t help it- she worried. It had taken her months to wrangle out an answer from the boy of his nightly activities- mainly _why_ he needed _so many dynamites_.

Learning he was a vigilante... wasn’t as shocking as she had expected. Yes, she was surprised, but it kind of _made sense_ , once you knew Katsuki. He wasn’t the law-abiding type, even if he rarely strayed from it. So far, she’d rightly deduced he had his own set of complex rules he followed. And he didn’t really step out of line- not using quirks meant not breaking the law. He should know, he had a lawyer for a mother.

But it didn’t mean she couldn’t worry. Sure, she knew very well he could take care of himself, but that did nothing to ease her worry. No matter how you look at it, he was still a child like her! And yet, here she was, in the safety of her bedroom, while he went off stopping crime in alleyways. She knew it wasn’t _wrong_ of her, he’d reassured her more than a few times, and she was intellectual enough to understand the difference in their skill- but it _hurt_ that she could only stay behind. Yes, she was better than kids her age, but _Katsuki_? Katsuki was better than _adults_.

It was what pushed her to study harder, to train more, to get even more smarter. She- she would admit she wasn’t used to this... being deadweight thing. Logically she knew she was helping, that she wasn’t deadweight or useless in any form- but it irked her that she couldn’t contribute _more_. She was used to being the best, not... a support. Yaomomo had been learning, but she wanted to _get into the action_.

Katsuki had promised he’d let her join when she was good enough- but he’d also hinted he would only let her join when she at least started middle school. Which would be two to three years from now. She was patient, but not _that_ patient.

So, she’d trained and trained and got into fights and tried VR and- not enough. Even she herself knew it wasn’t enough. She needed experience, but with Katsuki’s abilities limited as a child, he wouldn’t be able to protect her if they got into a fight. And she’d read lots of reports about people freezing up at their first few fights. It was why internships were so important in the Hero business.

Sometimes she doubted herself- scratch that, there was a _lot_ of times she doubted herself. But- but with Katsuki at her side, perhaps she might succeed. Even if she would always be chasing after him, she promised herself she would _never_ make him worry.

[][][][]

Izuku tossed and turned in his bed, waiting for his mom to go to sleep. When he was certain she was, he quietly sat up and opened the table-light. Rummaging through his drawer, he finally took out a hidden first-aid kit. Applying salve to his bruises, he took out his phone and tapped on a recording.

“ _...and we have the one and only Symbol of Peace here with us! All Might-san, could you say hi to our listeners?” “Ah, of course! Hello everyone! It’s my pleasure to be here.” “You flatter us, All Might-san! Now, we’ll start by asking...”_

Closing his eyes, he leant back into his bed as he listened to All Might’s interview.

[][][][]

Mitsuki carefully knocked on her son’s door. She’d made sure to hide her alarm clock this time. Ever since she started suspecting her son’s activities at night, she would wind up her alarm clock to midnight. But Katsuki, the brat, always found it and rewound it. This time, though, she’d made sure to hide it in somewhere her son would never look.

She slowly opened the door to her son’s bedroom. Instead of a slumbering blonde, all that was on his bed was a huge bolster covered in blankets, propped up in a mimic of the shadow of a body. She held back in a sob to find her theory proven correct. She had always known her son was trouble since the brat was born, but _this_...

She sat down on his empty bed to wait. She wouldn’t wake Masaru- god knows the man needed his rest. But she and her son were going to have a talk. She already knew she wouldn’t be able to convince him to back down- they were stubborn in the best and worse ways. They would _talk_ , and they would compromise. She sat, and waited.

[][][][]

Giran hummed as he finished his tea, eyes gliding over the most recent compilation of the new vigilante who’d approached him. He could still remember the first time they’d met. The kid had stared at him in shock, before a feral grin had overtaken his face. And then he’d shown him the fire.

Flames, he’d called them. Dying Will Flames. No matter how cheesy that sounded, it was oddly appropriate. Giran lifted a hand and watched as soft, indigo Flames bloomed from his palm. He’d discovered them- _activated_ them if the kid’s words were to be believed- when the first man literally out for his blood had come. He’d nearly _died_ , from a stab in the chest, before the Flames had erupted from him, roaring into an eldritch monster from the Cthulhu myths he’d been obsessed with when younger, and _devoured_ the man whole. Not a quirk, yet even more powerful...

How interesting. He’d experimented with it, and it was able to form all sorts of objects he wanted from varying degrees of success. The kid had made him a deal- he would provide the little vigilante with information he needed, and the brat would teach him to use his Flames. It seemed his life was going to get much more exciting. ‘The resurrection of the true Underground’, the boy had claimed. Well, in the chance of the boy succeeding, he would claim a spot for himself.

**Notes for the Chapter:**

> In case you need to know, they're nine at the start of the chapter, and ten after Naomasa's cameo. Y'all probably didn't see Giran coming, heh. I've always loved my information brokers, and collect them- Giran, Viper|Mammon, Izaya... the list goes on. Cough. 'Sides, Giran probably reminds Katsuki too much of the Mist Arcobaleno. He's good Quality too. Also, Naomasa is gonna be an important character after this- his Quirk's too fun. His sister too. Hope y'all liked this chapter!

**Author's Note:**

> I have no control. Do I care if I have other fics waiting to be updated? No. 
> 
> Many thanks to Wish_I_Was_Orochimaru and randomwaffle3 for being my betas! *throws kisses tearfully*


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